Im create a banner,but confuse where put this.
Which banner are you referring to? If you meant site logo - customize the template of the Top part of the website or the Style sheet CSS in Control panel: Design->Design management. Before customizing the template do the backup copy of the template in the menu item "Design”. But do not forget to upload your banner to your website via File Manager first.
If you meant the ad banner - use Builder to add the code of the banner into the block, created with Builder. See more about builder here: http://forum.ucoz.com/forum/5-5862-1#27866
-Moved to Design Customization-